Developing the Circular Water Economy
In our current economic model, manufactured capital, human capital, and natural capital all contribute to human welfare by supporting the production of goods and services in the economic process, where natural capital — the world’s stock of natural resources (provided by nature before their extraction or processing by humans) — is typically used for material and energy inputs into production and acts as a “sink” for waste from the economic process. This economic model can be best described as “linear” which typically involves economic actors — who are people or organizations engaged in any of the four economic activities of production, distribution, consumption, and resource maintenance — harvesting and extracting natural resources, using them to manufacture a product, and selling a product to other economic actors, who then discard it when it no longer serves its purpose.
While this model has generated unprecedented levels of growth, the model has led to resource scarcity, the generation of waste, and environmental degradation from a variety of climatic and non-climatic challenges. Climate change is impacting the availability of good quality water of sufficient quantities necessary for both humans and nature. Rapid population growth is increasing demand for food, which is placing immense stress on water resources, while agricultural production is impacting water quality. At the same time, economic growth and rising income levels are increasing demand for water resources, resulting in environmental degradation and biodiversity loss (Brears 2016, 2018b, 2020b). This chapter discusses the circular economy in general and in the context of water resources management. The chapter then discusses how the circular water economy can be enacted.
Circular Water Economy
The circular economy, in contrast to the linear “take-make-consume-dispose” economy, aims to decouple economic growth from resource use and associated environmental impacts. The notion of decoupling is that economic output shall continue to increase at the same time as rates of increasing resource use and environmental impact are slowed and in time brought into decline. In the context of water, the circular water economy aims to design out externalities and keep resources in use, all the while regenerating natural capital. Specifically:
- Designing out externalities: The circular water economy optimizes the amount of energy, minerals, and chemicals used in the operation of water systems in concert with other systems, optimizes consumptive use of water, and uses measures or solutions which deliver the same outcome without using water.
- Keeping resources in use: The circular water economy aims to optimize resource yields (water use and reuse, energy, minerals, and chemicals) within water systems, optimize energy or resource extraction from the water system and maximize their reuse, and optimize value generated in the interfaces of water systems with other systems.
- Regenerating natural capital: The circular water economy aims to maximize environmental flows by reducing consumptive and non- consumptive uses of water, preserve and enhance natural capital (e.g., pollution prevention, quality of effluent, etc.), and ensure minimum disruption to natural water systems from human interaction and use
Sacramento’s Harvest Water Project
Regional San, in collaboration with regional stakeholders, is developing Harvest Water. Harvest Water will provide multiple benefits, including providing safe and reliable supply of tertiary-treated water for agricultural uses, reducing groundwater pumping, and supporting habitat restoration efforts. Harvest Water proposes to use tertiary-treated recycled water on allowed crops (e.g. alfalfa, irrigated pastures, etc.) and irrigate permanent agricultural lands and habitat mitigation lands through new recycled water transmission and distribution systems. The amount of water saved would be the equivalent to the potable water needs of up to 100,000 homes in the Sacramento region. The programme will help conserve and protect surface water and groundwater supplies by reducing dependence on these resources. Recycled water could help raise groundwater levels enough to help bring increased flows back to the river, with modelling studies indicating that use of recycled water will help recharge the groundwater basin, potentially bringing a 20–30-foot rise in groundwater elevation.
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